Question Both monitors turn off and on repeatedly when playing games ?

[n0tr1m]

I have this problem where both of my monitors turn off and on repeatedly in a short period whenever I'm playing games. My main monitor is a fairly new LG LED monitor, while the second one is quite an old Samsung LED monitor. However, when I'm not playing video games, both of my monitors work perfectly, no problems whatsoever. I unplugged the second monitor and the main monitor works perfectly even when playing video games.


Here's the full spec
Main monitor: LG 24MP88HM
Second monitor: Samsung S22C300N
Processor: AMD Ryzen 5 2600 Six-Core Processor 3.4 GHz
Graphics Card: Inno3D Nvidia GeForce GTX 1070 Ti 8GB VRAM
RAM: 16 GB DDR4
Power Supply: 650 W 80+ Gold

What I've tried:

1. Unplugging both display cable from the GPU. This one works for a while, then the problem reappears not so long after.
2. Updating graphics card driver. No changes at all

Edit: For my main monitor, I'm using an HDMI cable. For my second monitor, I'm using a DP-to-VGA adapter, with the VGA plugged to the monitor.

 

[Ralston18]

Make and model PSU?

650 watts noted.

Age, condition (originally new, refurbished, used)?

History of heavy use for gaming?

 

[n0tr1m]

Make and model PSU?

650 watts noted.

Age, condition (originally new, refurbished, used)?

History of heavy use for gaming?

The PSU is probably around 2-3 years old. The make and model is Seasonic G-650 650W Modular 80+ Gold. I bought a new one from my local online shop.

Some hours ago from the time this reply is posted, I tried lowering the resolution of my second monitor from 1920x1080 to 1024x768 (native, in my case), and everything works perfectly even when gaming. My temporary conclusion is that somehow my power supply can't give enough power to both of the monitors if both of them are set to 1920x1080. I remember about a year ago my PC was struck by lightning, which totally destroyed my RAM (I even had to buy new ones), but might even damage my PSU in the process. I might try changing my power supply. But for now, I'm gonna stick to lowering my second monitor's resolution before launching my game.